Notes:
Most of these had pretty good sized caps, 8-10cm across) and were growing in a mixed hardwood area of the Big Sandy Creek Unit of the Big Thicket.
The spores were pink, flesh fairly soft, but I didn’t detect any bitterness typical of many Tylopilus species.The spores were medium sized,approx 11.0 X 6.0 microns.
The outstanding feature was the rapid dark reddish brown staining of the whitish pores. The flesh also bruised darkish brown fairly rapidly.
Couldn’t come up with an id to anything in the literature I have. The closest match in North American Boletes (Bessette et al.) was in the Undescribed section under “NAB-25”. There was no real description but they noted the “very dark bruising of the pore surface” and the colors appeared similar.

Comments

Had an e-mail correspondence with Bill Roody (co-author of North American Boletes) and he agrees that it looks like Tylopilus atronicotianus. In fact,
he says he thinks the Tylopilus NAB-25 is also Tylopilus atronicotianus and probably more typical of the species.